The production of bearing surfaces of crankshaft bearings (main bearings and pin bearings) is completed in multiple steps. In a first step the bearing surface is milled, and in a second step is ground to size. So-called finishing, which involves a lapping process, is carried out in a third step. In this regard a band-shaped tool (finishing belt) is generally used. Finishing is necessary to produce the desired slide path properties of the bearing surface. Unfinished crankshaft bearings generally fail. When a crankshaft bearing fails, it is necessary to disassemble the entire engine, which entails a high level of effort and correspondingly high costs.
To avoid failure of a crankshaft bearing, within the scope of producing the crankshaft the “finished” state and the “ground” state must be differentiated.
It is known to differentiate the ground/finished states by measuring suitable roughness parameters, for which tactile as well as optical methods are basically suitable.
In this regard, it is known in particular to examine the bearing surfaces using a scattered light sensor. Such a scattered light sensor scans the bearing surface to be tested and makes the ground/finished differentiation by means of a scattered light measurement. It is disadvantageous that such a scattered light measurement is relatively sensitive to fouling of the bearing surface, and at the same time requires high positioning accuracy of the crankshaft. Because such a scattered light sensor measures point by point, it is also necessary to move the scattered light sensor relative to the bearing surface. This requires a corresponding mechanical expenditure of effort.